Posted by Larry Hoover on February 14, 2005, at 14:48:55
In reply to Re: Vitamin D is likely better than a lightbox for SAD, posted by Shortelise on February 7, 2005, at 13:05:40
> Thanks again, Elaine.
>
> I've heard that if we go in the sun after bathing, we don't have the necessary stuff on our skin that converts to Vit D.
>
> ShortEUhhh, no, that would be a myth.
Cholesterol is the root of all steroid hormones. Pro-vitamin D is 7-dehydrocholesterol. Ultraviolet-B radiation from the sun (or a tanning bed) turns that into cholecalciferol (vitamin D3, but still not active). The liver converts that into a still-inactive substance called calcidiol (the 25(OH)D of the blood test). Only when the kidneys convert that to 1,25(OH)2D (calcitriol) is it in its active form.
Although "common wisdom" has it that vitamin D2 (ergocalciferol) from plant sources and vitamin D3 (cholecalciferol) from animal sources are metabolically interchangeable or bio-equivalent, recent evidence is indicating that may not be the case.
Anyway, there is nothing that happens during bathing that will reduce your capacity to form D3 from sunlight.
Lar
poster:Larry Hoover
thread:451955
URL: http://www.dr-bob.org/babble/alter/20050131/msgs/457704.html